In recent magnetic recording devices, methods have been devised to make the recording wave short and the track width narrow for a high recording density. In particular, video tape recorders have been proposed in enabling the remarkably high density recording.
Corresponding to the progress in the video tape recorder, there have been desired in a recording medium to improve the electro-magnetic conversion characteristics of a recording medium such as reproducing output, S/N ratio for obtaining clear picture quality and/or a high fidelity sound recording.
In order to improve the electro-magnetic conversion characteristics of a video tape, as the magnetic agents contained in the magnetic layer of the magnetic tape, there have been used, agents, such as magnetic powder of fine particles having a specific surface area more than 30 m.sup.2 /g, measured by a BET method.
As the magnetic powder of the kind mentioned above, ferrous magnetic powder, such as .gamma.-FeO.sub.3 and cobalt containing .gamma.-Fe.sub.2 O.sub.3, which is able to record and reproduce with a suitable remanence, may be generally be used and in fact a good electro-magnetic conversion characteristic can be obtained.
However, since the ferrous magnetic powder is brown or light brown in color, when the powder is contained in the magnetic layer of the recording tape with a specific surface area of more than 30 m.sup.2 /g, the recording tape is characterized with an inferior light shielding property in the magnetic layer.
Therefore, in a case where such a magnetic tape is used in a VHS type video tape recorder, in which an end of the tape is detected by an optical means is employed, there tends to occur an erroneous operation due to a high light transmittance of the recording tape.
In order to avoid this error, when a large amount of carbon black is contained in the magnetic layer, the electro-magnetic conversion characteristic and abrasion resistance may be harmed.
A video recording tape using chromium dioxide (CrO.sub.2) magnetic powder having specific surface area of more than 30 m.sup.2 /g measured by BET nitrogen method, has drawbacks. These being that the tape has a large surface roughness, a low electromagnetic conversion characteristic and there is a low abrasive resistance of the magnetic layer due to a low dispersibility of the CrO.sub.2 powder in the magnetic coating material.